Grate for ball mills and method of making same



F. E. MARCY May 24, 1927. 1,629,803

GRATE FOR BALL MILLS AND METHOD OF MAKING SAME Filed Nov. 22, 1926 2 Sheets-Sheet 1 HOD 0F IAKING SAME Patented May 24, 1927.

UNITED STATES PATENT OFFICE.

FRANK EARL MARCY, OF SAN DIEGO, CALIFORNIA.

GRATE non BALL MILLS AND METHOD or MA nvG SAME.

Application filed November 22;. 1926. Serial No. 150,0'i2.

This invention relates to an improvement in grates which are used in ball mills for crushing ores or thelike. In one type of such mill there is placed near the discharge end a separating screenor grate to allow the properly ground material to pass out.

This general type of mill is shown in my Patent 1,153,289, September 14, 19l5,'and

the present invention is an improvement on their frame.

It is an object of this invention to provide a grate' in which the grate bars are rigidly and firmly secured to the supporting frame.

Another object of the invention is to provide a grate wherein the bars are so secured that they cannot work loose when they are worn down in use.

These and other objects will be apparent from the following description taken in connection with the accompanying drawings wherein Fig. 1 is a front. elevation of a completed grate section, with one corner broken away;

Fig. 2 is a fragmentary sectional view, showing the means of connecting the grate sections to a spider frame;

Fig. 3 is an enlarged fragmentary end view of an end of the. grate, one grate bar being partly broken away, and I Fig. i is a similar fragmentary view of a modified form.

The assembled grate bars, as shown in Fig. 1, comprise one of a series of similar members arranged about a common axis, as

is clearly shown in my Patent 1,153,239, September 14, 1915. Numeral 1 indicates the individual grate bars, which are made progr-essively shorter, as seen in Fig. 1, and are preferably made of special high carbon, chrome steel. Each end of these grate bars is formed at an angle to the longitudinal axis of the bar, so that one edge is longer than the other. These sloping ends make an angle of approximately 66 with the longitudinal faces, or in other words angle 'A (see Fig. 3) is about 66.

Also, the bars' may slip endwise and fall completely out of These sloping end faces of the bars are further cut back, as seen in Figs. 2 and 3, to provide a projecting lug or lip 2 at the rear of the bars.

The individual grate bars are aligned in parallel relation and properly spaced from one another as seen in Fig. 1. and a crossrod of metal 3, preferably steel, is placed upon these projecting lugs or lips, said rod having upset ends 4. In Fig. 1, two longitudinally aligned cross-rods are shown on each side of the completed grate section,

but it is obvious that this is not-essential, as 1n some cases only one rod may be needed, or possibly three or more rods. \Vith the grate thus assembled, a steel jacket or hinder 5 is then cast around the ends of each grate bar. This jacket completely encloses the cross-rods and the ends of the grate bars, and extends between the separated bars a distance equal to the cut-back on the ends of the bars. This will be clear from Figs.- 3

' and at wherein the front grate bar is broken mg arms 6 which are engaged by the rear.

faces of adjacent lateral edges of each two grate sections, as seen in Fig.2. A clamp bar or member 7 is placed between adjacent grate section, said member having openings 8 therethrough to receive bolts 9, having heads 10. The bolts 9 pass through the spider 6 and openings 8 are countersunk to take heads 10. At their other ends the bolts are screw-threaded to receive nuts 11 for engagement against face 12 of the spider 6.

The material which has been ground passes horizontally through the grate (or from above, as seen in Fig. 2).

The front surface of the grate section wears away in use, and the cast metal fins may become separated from the adjacent grate bars. The transverse steel rods lock the cast metal in place to prevent relative displacement'of the bars and cast metal. The grates may therefore be used until worn so thin as to be structurally Weak.

The embodiment shown is for illustrative purposes only, and the invention is limited only in so far as set forth in the following claims.

I claim 1. The method of uniting a plurality of grate bars, having a projecting lug at each end thereof into a rigid grate section, which comprises arranging the bars in parallelism with the projecting lugs at the respective ends of the bars in alignment placing a metallic rod along the ends of the bars and resting on said lugs, and casting a steel binder along the ends of the bars and enclosing said rod. 7

2. A grate section for ball mills comprising, in combination, a plurality of grate bars in parallelism, the ends of the bars being recessed to provide lips on the ends, a steel rod resting on the aligned lips at each end oi the bars, and a side strip of metal cast upon and enclosing each of said rods and the bar ends adjacent thereto.

3. The structure as in claim 2 wherein the lips on the ends of the bars are hook shaped.

4. The structure as in claim 2 wherein the ends of the steel rods are upset.

5. A grate section for ball mills of the type wherein, a plurality of grate bars are held rigidly in parallel spaced relation, characterized by the fact that the ends of the bars are joined by means of a steel binder cast upon the ends of the bars and having embedded therein a transverse steel rod.

6. A grate section for ball mills of the type Whereina plurality of grate bars are held in parallel spaced relation, character ized by the fact that the bars are provided with aprojecting lug on each end and across rod, having upset ends, is held in rigid engagement with said lugs by an encasing steel jacket cast in situ.

7. A grate section for ball mills of the type wherein a plurality of rate bars are held in rigid parallelism, by binding strips of metal cast upon the ends thereof, characterized by the fact that each grate bar has an overhanging hookon its ends, and a steel rod is engaged by the said hooks, said metallic binding strip enclosing said hooks and the steel rod. i

8. A grate section comprising a plurality of grate bars in spaced and substantially parallel relation, a body of metal cast upon said bars and having fins extending between adjacent bars to retain the same in said spaced relation, and a rod embedded in said cast metal, said rod preventing displacement of individual fins of cast metal if the bond between the fin and an adjacent bar is destroyed.

In testimony whereof, I afi'ix mysignature. v

FRANK EARL MABCY. 

